Reversible coal cutting bit



March 2, 1943. I c FoRB s 2,312,538

REVERSTBLE COAL CUTTING BIT Filed Jan. 16, 1942 I I (I///I/ 9-- Q 1- 3mmall 0 7&6 5

Patented Mar. 2, 1943 warren stares ear nr @FFHQE REVERSEBLEL COALCUTTING BIT Charles J. Forbes, Terre Haute, Ind.

Application January 16, 1942, Serial No. 427,049

1 Claim. (Cl. 262-33) This invention relates generally tomining'machinery, and more especially to new and useful improvements inthe cutter bit and means for mounting the bit in the cutter chain block.

It is a Well recognized fact that the average cutter bit is subjected toextremely hard usage and constant replacement is necessary. For thisreason, it is desirable that the cutter bit be reversible and that bothends of the bit be cutting ends. Further, it is important that simpleand eiiective holding means be provided which will facilitate inserting,reversing or replacing the cutter bit under any and all conditions.

One object of my present invention, therefore, is to provide areversible cutter bit formed at diagonally opposite ends or points withcutting teeth.

A further object of my invention is to provide improved holding meansassociated and co-acting with the cutter bit for holding the lattersecurely in place under all conditions, but at the same time allowingthe cutter bit to be easily and readily reversed or replaced, asoccasion requires.

A still further object of my invention is to provide a novelconstruction of the character specified, in which the base of the cutterbit is sup ported by and rests firmly on the upper edge of the cutterchain block.

With the foregoing and other objects in View that will appear as thenature of my invention is better understood, the same consists in thenovel features of construction, combination and arrangement of partsillustrated in the accompanying drawing and more particularly pointedout in the appended claim.

In the accompanying drawing, which is for 11- lustrative purposes anlyand are therefore not drawn to scale:

Figure 1 is a side elevation, illustrating the application of myinvention.

Figure 2 is an enlarged detail fragmentary sectional View of the cutterbit, bit holder and upper end of the chain block.

Figure 3 is an enlarged vertical transverse section, taken on line 3-3of Figure 1, looking in the direction indicated by the arrows.

Figure 4 is an enlarged detail horizontal section, taken on line 44 ofFigure 1.

Figure 5 is an enlarged detail perspective view of the cutter bit.

Figure 6 is an enlarged detail diagonal section, taken on line 6-6 ofFigure 1 and Figure 7 is a view similar to Figure 2 of the drawing,showing a modified form of my invention.

Referring to the drawing for a more particular description of myinvention, and in which drawing like parts are designated by likereference characters throughout the severalviews, A designates thecutter chain block, B the reversible cutter bit and C the bit holder.

The reversible cutter bit is preferably formed from rolled stock and isof general triangular shape. Said bit is preferably one inch in width,three-eighths of an inch in thickness at the center of the base andtapers to a thickness having a radius of three sixty-fourths of an inchat its outer diagonal edge. The base I of the cutter bit is supported byand rests firmly on top of the cutter chain block A, as shown and thehead 2 of the bit holder C, is formed with a horizontal transverse slotor opening 3 to receive the bit. The opening 3 is somewhat greater inWidth than the co-acting portion of the cutter bit to facilitatereversal and replacement of the latter, as will presently appear.

In carrying out my invention, the outer diagonal edge 4 of the cutterbit is formed with a central arcuate recess 5, adapted to receive andco-act with the convex boss 6, formed on the outer wall of thetransverse slot or opening 3 in the bit holder 0, in holding the bitfirmly in place in the latter. The bit holder C is provided with theintegral depending shank l, which fits in a broached opening 8 in thecutter chain block A, and is formed in one edge with a recess 9, adaptedto be engaged by the inner end of the screw I 0. The screw I0 is carriedby one edge of the cutter chain block and holds the shank of the bitholder securely in place.

The reversible cutter bit comprises the fiat horizontal base i, which,as previously mentioned, rests firmly on the upper edge of the cutterchain block A, the fiat side edge H, which is disposed at an angle ofthirty degrees with the base, and the outer diagonal edge 4, which eX-tends between the outer ends of the base and side edge II. The oppositeside faces of the cutter bit are tapered from the base I and side edgeI! to the outer diagonal edge 4 of the bit to three sixty-fourths of aninch in thickness, forming the diagonally opposed cutting teeth I2. Itwill be noted that the cutter bit is curved or rounded at the apex ofthe triangle, as at 13,

' that is to say, at the corner that would ordinarily be formed at theinner ends of the base and side edge H.

My improved construction is such that the cutter bit is not only capableof double use and held firmly in position on the cutter block, but issusceptible of easy and ready reversal or replacement, as may berequired under actual operating conditions. This reversibility andreplacement is made possible by making the transverse slot or opening 3in the bit holder C of greater width than the corresponding or engagingportion of the bit to permit dis-engagement and separation of thearcuate recess 5 and boss 6, after first dis-engaging the inner end ofthe screw l0 with the recess 9 of the shank 1.

In'the modified form of my invention illustrated in Figure 7 of thedrawing, the outer diagonal edge 4 of the cutter bit B is not formedwith a central arcuate recess 6, but is made solid and formed with acentral convex boss I4, which fits in a corresponding recess l5, formedin the outer wall of the transverse slot or opening 3 in the bit holder.In other words, the construction is substantially the reverse 1 off,that shown in Figures 1 and 2 of the drawing, in this particular.

From the foregoing description taken rin connection with the drawing, itis thought that the construction, operation and advantages of myinvention, will be readily understood, without requiring a more extendedexplanation.

Various changes in the form, proportions and minor details ofconstruction may be resorted to without departing from the principle orsacrificing any of the advantages of my invention, as defined in theappended claim.

Having described my invention, what I claim as new and desire to secureby Letters Patent, is: In a device of the character specified, a cutterchain block having a vertical socket, a bit holder having a shankextending into said socket and a head formed with a transverse slot oropening, a reversible cutter bit of general triangular form, mounted onthe cutter chain block and extending through the opening in the bitholder, said cutter bit having a straight diagonal outer edge formedwith a central arcuate recess extending approximately one-third of thelength of said outer edge, and said cutter bit being curved or roundedofi at its apex, a convex boss formed on the outer wall of thetransverse slot or opening in the bit holder and coacting with saidarcuate recess in holding the cutter bit securely in place, and meansfor securing the cutter bit in the cutter chain block, the transverseslot or opening in the head of the bit holder being of greater Widththan the received portion of the cutter bit to allow separation of theco-acting recess and boss preparatory to reversal or replacement of theformer.

CHARLES J. FORBES.

